Glucocorticoids(GCs)are involved in the regulation of an animal's energetic state.Under stressful situations,they are part of the neuroendocrine response to cope with environmental challenges.Animals react to aver...Glucocorticoids(GCs)are involved in the regulation of an animal's energetic state.Under stressful situations,they are part of the neuroendocrine response to cope with environmental challenges.Animals react to aversive stimuli also through behavioral responses,defined as coping styles.Both in captive and wild populations,individuals differ in their behavior along a proactive-reactive continuum.Proactive animals exhibit a bold,active explorative and social personality,whereas reactive ones areshy,less active-explorative and less social.Here,we test the hypothesis that personality traits and physiological responses to stressors covary,with more proactive individuals having a less pronounced GC stress response.In wild populations of invasive gray squirrels Sciurus carolinensis,we measuredfecal glucocorticoid metabolites(FGMs),an integrated measure of circulating GCs,and 3 personality traits(activity,sociability,and exploration)derived from open field test(OFT)and mirror image stimulation(MIS)test.Gray squirrels had higher FGMs in Autumn than in Winter and males with scrotal testes had higher FGMs than nonbreeding males.Personality varied with body mass and population density.Squirrels expressed more activity exploration at higher than at lower density and heavier squirrels had higher scores for activity exploration than animals that weighed less.Variation in FGM concentrations was not correlated with the expression of the 3 personality traits.Hence,our results do not support a strong association between the behavioral and physiological stress responses but show that in wild populations,where animals experience varying environmental conditions,the GC endocrine response and the expression of personality are uncorrelated traits among individuals.展开更多
Short-term elevation of glucocorticoids(GCs)is one of the major physiological mechanisms by which vertebrates cope with challenging environmental or social factors(stressors).However,when exposure to stressors occurs ...Short-term elevation of glucocorticoids(GCs)is one of the major physiological mechanisms by which vertebrates cope with challenging environmental or social factors(stressors).However,when exposure to stressors occurs repeatedly or over a prolonged period of time,animals may experience chronic elevation of GCs,which reduces the immune response efficiency and can lead to higher intensity of parasitic infection.Here,we used invasive gray squirrels Sciurus carolinensis in troduced in Norther n Italy and their 2 most prevale nt gastrointesti nal parasites,the n ematode Strongyloides robustus and coccidia of the genus Eimeria,as a model to investigate relati on ships among macroparasite infection and concentrations of fecal glucocorticoid metabolites(FGMs),an integrated measure of circulating GCs.Our results revealed an association of FGMs with infection by St.robustus,but not with coccidia.Individuals with higher FGMs appear to be responsible for the greatest St.robustus egg shedding within gray squirrel populations,thus possibly acting as superspreaders.However,FGMs were negatively associated with adult St.robustus,suggesting that the abundance of adults of this nematode species does not induce elevation in FGMs,but is only affected by it through immun e-mediated effects on its fecun dity.Fin ally,the relati on ship betwee n St.robustus(both eggs and adult parasites)and FGMs was not linear,suggesting that only high levels of physiological stress in fluence parasite inf ection.Our fin dings highlight that the direction and magnitude of the stress-infection relationship may depend not only on the specific hostparasite system,but also on the different life stages of the same parasite.展开更多
Determining how animals respond to resource availability across spatial and temporal extents is crucial to understand ecological processes underpinning habitat selection.Here,we used a multi-scale approach to study th...Determining how animals respond to resource availability across spatial and temporal extents is crucial to understand ecological processes underpinning habitat selection.Here,we used a multi-scale approach to study the year-round habitat selection of the Crested Tit(Lophophanes cristatus)in a semi-natural lowland woodland of northern Italy,analysing different habitat features at each scale.We performed Crested Tit censuses at three different spatial scales.At the macrohabitat scale,we used geolocalized observations of individuals to compute Manly's habitat selection index,based on a detailed land-use map of the study area.At the microhabitat scale,the trees features were compared between presence and absence locations.At the foraging habitat scale,individual foraging birds and their specific position on trees were recorded using focal animal sampling.Censuses were performed during both the breeding(March to May)and wintering(December to January)seasons.At the macrohabitat scale,the Crested Tits significantly selected pure and mixed pine forests and avoided woods of alien plant species,farmlands and urban areas.At the microhabitat scale,old pine woods with dense cover were selected,with no significant difference in the features of tree selection between the two phenological phases.At the foraging habitat scale,the species was observed spending more time foraging in the canopies than in the understorey,using mostly the portion of Scots Pine(Pinus sylvestris)canopies closer to the trunk in winter,while during the breeding period,the whole canopy was visited.Overall,breeding and wintering habitats largely overlapped in the Crested Tit.Based on our findings,lowland Crested Tits can be well defined as true habitat specialists:they are strictly related to some specific coniferous woodland features.Noteworthily,compared to other tit species,which normally show generalist habits during winter,the Crested Tit behaves as a habitat specialist also out of the breeding season.Our study stressed the importance of considering multi-scale(both spatial and phenological)habitat selection in birds.展开更多
Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species,which can result in habitat-dependent phenotypic differences among animals living in heterog...Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species,which can result in habitat-dependent phenotypic differences among animals living in heterogeneous environments.We studied 3 alpine populations of Eurasian red squirrels(Sciurus vulgaris),1 living in a marginal high-elevation habitat at the edge of the species’altitudinal distribution,and 2 occurring in higher-quality habitats.Here,we investigated whether squirrels living in the marginal area differed in 2 morphological parameters(body size and body mass)and/or in the expression of 4 personality traits estimated with an openfield test and a mirror image stimulation test(activity,exploration,activity-exploration,and social tendency).Furthermore,we tested whether within-individual variance of the traits(behavioral plasticity)was higher in the edge habitat.Male squirrels in the edge habitat were smaller and weighed less than in the other study areas,while among females,size–habitat relationships were less marked.These sex-specific patterns were explained by a strong association between body mass and reproductive success in female squirrels.Squirrels in the marginal habitat were more active,explorative,and had a more social personality than in the other habitats.However,in contrast to our predictions,behavioral plasticity was smaller in the marginal habitat,but only for the trait exploration.Our results suggest that animals choose the habitat that bestfits their personality,and that habitat-related differences in selective pressures may shape animals’morphology.展开更多
Integrative taxonomy,a multi-disciplinary approach adding modern techniques to traditional morphology-based methods(e.g.molecular and morphological criteria),can play an important role in bioinvasion research to ident...Integrative taxonomy,a multi-disciplinary approach adding modern techniques to traditional morphology-based methods(e.g.molecular and morphological criteria),can play an important role in bioinvasion research to identify introduced taxa,discover pathways of introduction and inform authorities to control and prevent future introductions.The present study is the first on introduced populations of Callosciurus,Asiatic tree squirrels,known as potentially invasive species in Europe(Italy,Belgium and France).We combined molecular(mitochondrial DNA markers:CoxI,D-loop)and morphometric analysis on skulls,comparing them to the widest morphological and molecular datasets ever assembled for Callosciurus.Squirrels collected in Italy and Belgium share the same haplotypes and skull characteristics,but are conspicuously different from the French population in Antibes.Genetic data revealed close similarity between French squirrels and Pallas’s squirrels,Callosciurus erythraeus,from Taiwan,China.Italian and Belgian squirrels formed an independent taxonomic lineage in genetic analyses,whose taxonomic rank needs further investigation.The morphological and morphometric characteristics of these 2 populations are,however,similar to known specimens assigned to Callosciurus erythraeus.These results may indicate a common origin for the populations found in Belgium and Italy.In contrast,French specimens suggest an independent introduction event of squirrels originating from Asia.展开更多
The study of the relationship between animal stress and personality for free-ranging animals is limited and provides contrasting results.The perception of stressors by an individual may vary due to its personality,and...The study of the relationship between animal stress and personality for free-ranging animals is limited and provides contrasting results.The perception of stressors by an individual may vary due to its personality,and certain personality traits may help individuals to better cope with them.Using non-invasive infrared thermography(IRT),we investigated the link between physiological and behavioral components expressed during an acute stress event by free-ranging Fremont’s squirrels(Tamiasciurus fremonti).We expected that,during the acute stress event of being approached by the researcher,individuals that showed a fast pace-of-life syndrome(bolder,more active,and less social/more aggressive)based on an arena test would exhibit stronger sympathetic-adrenal-medullary system reactivity showing a more intense stress-induced hyperthermia(high core body temperature and low peripheral temperature)than individuals with a slow pace of life(shy,less active,and more social).We successfully employed IRT technology to images of Fremont’s squirrels with identification of the individuals’body parts(eye,nose,ear,hind foot).However,we found no support for our hypothesis.Squirrels’body surface temperatures told us more about a squirrel’s external environment and less about the thermal state of the body in that environment following a stressful event.Further studies need to assess how to make IRT effective and efficient in the field and improve its performance in studying the relationships between physiology and personality in wildlife.展开更多
文摘Glucocorticoids(GCs)are involved in the regulation of an animal's energetic state.Under stressful situations,they are part of the neuroendocrine response to cope with environmental challenges.Animals react to aversive stimuli also through behavioral responses,defined as coping styles.Both in captive and wild populations,individuals differ in their behavior along a proactive-reactive continuum.Proactive animals exhibit a bold,active explorative and social personality,whereas reactive ones areshy,less active-explorative and less social.Here,we test the hypothesis that personality traits and physiological responses to stressors covary,with more proactive individuals having a less pronounced GC stress response.In wild populations of invasive gray squirrels Sciurus carolinensis,we measuredfecal glucocorticoid metabolites(FGMs),an integrated measure of circulating GCs,and 3 personality traits(activity,sociability,and exploration)derived from open field test(OFT)and mirror image stimulation(MIS)test.Gray squirrels had higher FGMs in Autumn than in Winter and males with scrotal testes had higher FGMs than nonbreeding males.Personality varied with body mass and population density.Squirrels expressed more activity exploration at higher than at lower density and heavier squirrels had higher scores for activity exploration than animals that weighed less.Variation in FGM concentrations was not correlated with the expression of the 3 personality traits.Hence,our results do not support a strong association between the behavioral and physiological stress responses but show that in wild populations,where animals experience varying environmental conditions,the GC endocrine response and the expression of personality are uncorrelated traits among individuals.
基金Thanks to Zainab Almusawi and Teera Losch for helping in laboratory analysis,Candice Gagnaison,Laure Vanlauwe,and Mattia Panzeri for assistance with the fieldwork.We are grateful to the private land owners for access to their estates.Three anonymous reviewers provided constructive comments that helped us to improve the article.
文摘Short-term elevation of glucocorticoids(GCs)is one of the major physiological mechanisms by which vertebrates cope with challenging environmental or social factors(stressors).However,when exposure to stressors occurs repeatedly or over a prolonged period of time,animals may experience chronic elevation of GCs,which reduces the immune response efficiency and can lead to higher intensity of parasitic infection.Here,we used invasive gray squirrels Sciurus carolinensis in troduced in Norther n Italy and their 2 most prevale nt gastrointesti nal parasites,the n ematode Strongyloides robustus and coccidia of the genus Eimeria,as a model to investigate relati on ships among macroparasite infection and concentrations of fecal glucocorticoid metabolites(FGMs),an integrated measure of circulating GCs.Our results revealed an association of FGMs with infection by St.robustus,but not with coccidia.Individuals with higher FGMs appear to be responsible for the greatest St.robustus egg shedding within gray squirrel populations,thus possibly acting as superspreaders.However,FGMs were negatively associated with adult St.robustus,suggesting that the abundance of adults of this nematode species does not induce elevation in FGMs,but is only affected by it through immun e-mediated effects on its fecun dity.Fin ally,the relati on ship betwee n St.robustus(both eggs and adult parasites)and FGMs was not linear,suggesting that only high levels of physiological stress in fluence parasite inf ection.Our fin dings highlight that the direction and magnitude of the stress-infection relationship may depend not only on the specific hostparasite system,but also on the different life stages of the same parasite.
文摘Determining how animals respond to resource availability across spatial and temporal extents is crucial to understand ecological processes underpinning habitat selection.Here,we used a multi-scale approach to study the year-round habitat selection of the Crested Tit(Lophophanes cristatus)in a semi-natural lowland woodland of northern Italy,analysing different habitat features at each scale.We performed Crested Tit censuses at three different spatial scales.At the macrohabitat scale,we used geolocalized observations of individuals to compute Manly's habitat selection index,based on a detailed land-use map of the study area.At the microhabitat scale,the trees features were compared between presence and absence locations.At the foraging habitat scale,individual foraging birds and their specific position on trees were recorded using focal animal sampling.Censuses were performed during both the breeding(March to May)and wintering(December to January)seasons.At the macrohabitat scale,the Crested Tits significantly selected pure and mixed pine forests and avoided woods of alien plant species,farmlands and urban areas.At the microhabitat scale,old pine woods with dense cover were selected,with no significant difference in the features of tree selection between the two phenological phases.At the foraging habitat scale,the species was observed spending more time foraging in the canopies than in the understorey,using mostly the portion of Scots Pine(Pinus sylvestris)canopies closer to the trunk in winter,while during the breeding period,the whole canopy was visited.Overall,breeding and wintering habitats largely overlapped in the Crested Tit.Based on our findings,lowland Crested Tits can be well defined as true habitat specialists:they are strictly related to some specific coniferous woodland features.Noteworthily,compared to other tit species,which normally show generalist habits during winter,the Crested Tit behaves as a habitat specialist also out of the breeding season.Our study stressed the importance of considering multi-scale(both spatial and phenological)habitat selection in birds.
文摘Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species,which can result in habitat-dependent phenotypic differences among animals living in heterogeneous environments.We studied 3 alpine populations of Eurasian red squirrels(Sciurus vulgaris),1 living in a marginal high-elevation habitat at the edge of the species’altitudinal distribution,and 2 occurring in higher-quality habitats.Here,we investigated whether squirrels living in the marginal area differed in 2 morphological parameters(body size and body mass)and/or in the expression of 4 personality traits estimated with an openfield test and a mirror image stimulation test(activity,exploration,activity-exploration,and social tendency).Furthermore,we tested whether within-individual variance of the traits(behavioral plasticity)was higher in the edge habitat.Male squirrels in the edge habitat were smaller and weighed less than in the other study areas,while among females,size–habitat relationships were less marked.These sex-specific patterns were explained by a strong association between body mass and reproductive success in female squirrels.Squirrels in the marginal habitat were more active,explorative,and had a more social personality than in the other habitats.However,in contrast to our predictions,behavioral plasticity was smaller in the marginal habitat,but only for the trait exploration.Our results suggest that animals choose the habitat that bestfits their personality,and that habitat-related differences in selective pressures may shape animals’morphology.
文摘Integrative taxonomy,a multi-disciplinary approach adding modern techniques to traditional morphology-based methods(e.g.molecular and morphological criteria),can play an important role in bioinvasion research to identify introduced taxa,discover pathways of introduction and inform authorities to control and prevent future introductions.The present study is the first on introduced populations of Callosciurus,Asiatic tree squirrels,known as potentially invasive species in Europe(Italy,Belgium and France).We combined molecular(mitochondrial DNA markers:CoxI,D-loop)and morphometric analysis on skulls,comparing them to the widest morphological and molecular datasets ever assembled for Callosciurus.Squirrels collected in Italy and Belgium share the same haplotypes and skull characteristics,but are conspicuously different from the French population in Antibes.Genetic data revealed close similarity between French squirrels and Pallas’s squirrels,Callosciurus erythraeus,from Taiwan,China.Italian and Belgian squirrels formed an independent taxonomic lineage in genetic analyses,whose taxonomic rank needs further investigation.The morphological and morphometric characteristics of these 2 populations are,however,similar to known specimens assigned to Callosciurus erythraeus.These results may indicate a common origin for the populations found in Belgium and Italy.In contrast,French specimens suggest an independent introduction event of squirrels originating from Asia.
文摘The study of the relationship between animal stress and personality for free-ranging animals is limited and provides contrasting results.The perception of stressors by an individual may vary due to its personality,and certain personality traits may help individuals to better cope with them.Using non-invasive infrared thermography(IRT),we investigated the link between physiological and behavioral components expressed during an acute stress event by free-ranging Fremont’s squirrels(Tamiasciurus fremonti).We expected that,during the acute stress event of being approached by the researcher,individuals that showed a fast pace-of-life syndrome(bolder,more active,and less social/more aggressive)based on an arena test would exhibit stronger sympathetic-adrenal-medullary system reactivity showing a more intense stress-induced hyperthermia(high core body temperature and low peripheral temperature)than individuals with a slow pace of life(shy,less active,and more social).We successfully employed IRT technology to images of Fremont’s squirrels with identification of the individuals’body parts(eye,nose,ear,hind foot).However,we found no support for our hypothesis.Squirrels’body surface temperatures told us more about a squirrel’s external environment and less about the thermal state of the body in that environment following a stressful event.Further studies need to assess how to make IRT effective and efficient in the field and improve its performance in studying the relationships between physiology and personality in wildlife.
